docs: def alpha_view(qimage):
      """Returns alpha view of a given 32-bit color QImage_'s memory.
      The result is a 2D numpy.uint8 array, equivalent to
      byte_view(qimage)[...,3].  The image must have 32 bit pixel size,
      i.e. be RGB32, ARGB32, or ARGB32_Premultiplied.  Note that it is
      not enforced that the given qimage has a format that actually
      *uses* the alpha channel -- for Format_RGB32, the alpha channel
      usually contains 255 everywhere.
  
      For your convenience, `qimage` may also be a filename, see
      `Loading and Saving Images`_ in the documentation.
  
      :param qimage: image whose memory shall be accessed via NumPy
      :type qimage: QImage_ with 32-bit pixel type
      :rtype: numpy.ndarray_ with shape (height, width) and dtype uint8"""
      bytes = byte_view(qimage, byteorder = None)
      if bytes.shape[2] != 4:
          raise ValueError("For alpha_view, the image must have 32 bit pixel size (use RGB32, ARGB32, or ARGB32_Premultiplied)")
      return bytes[...,_bgra[3]]